Preparation of clarified sugar solutions



we N v- 18. 2,431,163

'rA'rss ATENT OFFICE PREPARATION OF CLARIFIED SUGAR SOLUTIONS Robert M. Boehm. Laurel, Miss., and Horace E.

Hall, Lyle, Tenn., assignors to Masonite Corporation, Laurel, Miss a corporation of Delawere No Drawing. Application March 31, 1944,

- Serial No. 529,036

8 Claims. (Cl. 195-84) 1 2 This invention relates to a process for the 20 pounds per square inch, with addition of acid preparation of sugar solutions in such clarified catalytic material consisting of preferably about state that they are well adapted iorfermentation 1% of H2804 by weight of the liquor, which acid, or like treatment, to produce organic compounds together with acids in the liquor. brings about such as acetone, butyl alcohol, acetic acid and 5 precipitation of the dispersed or colloidal matthe like. It relates more especially to the preparater, and also efiects the conversion of hexose and tion of such sugarsolutions from liquors derived pentose precursors to hexose and pentose sugars. from wood or woody materials, hereinafter called The mild conditions of hydrolysis avoid substanwood liquors. The practice of the process will tial degradation of the sugars and prevent undue he described upon wood liquors obtained by exformation of additional tars or of furfural, both pression or washing from fiber, which fiber was of which are toxic to fermentation. produced by subjecting wood chips in a gun, such In order to collect and remove as much as posas described in U. 8. Patent 1,824,221 to Mason, to sible of the tars which ordinarily are present or the hydrolyzing action of high-pressure steam, fo S e extent during e m l hydroly i followedby explosive discharge from the gun. treatment, finely divided material may be added Such a liquor is described in U. s. Patent No. to the liquor p i to y s- 'ii'c ys 2,224,135 to Boehm. and the like may be used for this purpose. The

When sugar solutions for fermentation are preferr d fine ri v sists f soprepared from such wood liquor by previously- Called lud v ry fine l d particles of wood known procedure, difliculties are encountered in fiber, etc., contained in and obtainable from the the fermentation treatment thereof by the ferwaste materials from fiberboard manufacturin orienting organisms being apparently i o d processes. Such sludge material is described in by toxic compounds which are present. U. S. Patent 2,080,077 to Howard et al.

It is an object of this invention to provide a The precipitated material, tfigether with y process of treating wood liquors to prepare sugar added sludge or other finely divided material, is solutions for fermentation by which materials r d fIOm t e l y filtering he liquor toxic to fermentation are removed and the inis thus P Satisfactory Condition or e hibition of fermentation is avoided. t n y water-mmiscihle So e ts.

[i further object consists in the provision of The filtrate thus secured is preferably subjected such a process wherein a sulfide precipitatio is 39 to solvent extraction for removal of tars, organic made use of to remove materials toxic t f r acids, traces of furfural, and the like. Preferred tation. solvents found suitable for this purpose are butyl The wood liquor obtained as described contains alcoh-cior iurfural, altho other Sui ble wateriemicellulosic materials made soluble in water immiscible Solvents mixtures of Solvents. Such is the high-pressure steam treatment. From as ethyl fi p flp l ether may be used.

t e's materials hexos and pentose. sugars may Solvent extraction is preferably carried out by be formed, and such precursors of hexose and counter-current washing with the solvent in a pentose are herein referred to as hexosans and liquid-liquid extract. and the o ent is recovpentosans. The liquor also contains other organic cred for re-use after removal and recovery of materials such as solubl or dispersed t acetic 40 solved materials such as tars, acetic acid, furfural acid, formic acid, soluble or dispersed llgin or and the like. Solvents remaining dissolved in the ileum-degradation products, astringents, and treated liquor are desirably removed in a pvarious other materials, some or all of which, and s u n y ans of st am and recovered for especially the astringents, must be removed bee-use in the customary manner. l tore sugar solutions will be obtained in condition The extraction and Stripping treatments 3 for fermentation and the like treatment. Preferably Supplemented by treatment with acti- The presence of dispersed or colloidal material vated carbon. Such treatment may be carried out in such liquor makes extraction treatment with by adding activated carbon in subdivided state water-immiscible solvents, for removal of tars, t0 the q followed y fi rin o t the carbon organic acids and the like, diiilcult or impossible to and adsorbed material Used i s ay. the due to tendency toward emulsification. carbon can be cleaned and re-used, if desired. If

The liquor is first subjected to mild hydrolysis desired, this treatment with carbon can be perto convert the hexosans and pentosans to sugars, formed in whole or in part at a later stage, as as for example by cooking for about thirty to will be described later. forty minutes with steam at a pressure of about At this' stage the liquor is acidic, having for example a pH of about 8 to 4 due to the presence of the acid such as H2804 used for catalyzing the hydrolysis treatment. It also contains materials which are toxic to fermentation, and which may include tannins or other materials that. are apparently of astringent character, as indicated by a bitter or puckery taste. Such toxic materials will be referred to as astrlngents. If fermenta tion of the liquor is attempted at this stage, satis= factory results. are not obtained apparently due to presence of toxic materials, especially astringents.

By the present invention such liquors are prepared for fermentation by a treatment consisting in adding to the acid liquor a metal, such as iron or aluminum, preferably in subdivided state, or a salt of the metal, followed by the addition of alkaline material, preferably lime, and then, if desired, subjecting the liquor to a further treatment with His. a

The metals or salts thereof will react with the sulfuric acid to form water-soluble metal sulfates. Following the introduction of the metal or salt, sumcient alkaline material, preferably lime, is added to bring the liquor to the alkaline side, as to a pH of about 7.5 to 8.5. Any materially higher I alkalinity than pH of about 8 is to be avoided because it may cause redissolving of the precipitate.

This treatment results in'a voluminous precipitation of the metal hydroxide, together with calcium sulfate. Upon filtering out this precipitate, which is comparatively gelatinous, the liquor is found to be substantially free from previous bitter or puckery taste and in improved condition for fermentation. Whether under these conditions there is a reaction between the metal and the organic astringent materials, or whether the astringent materials are carried down mechanically with the precipitate above referred to, or both, is not known, but in any event the described improvement in the liquor is attained. Ifthe liquor is to be subjected to fermentation at this stage, its pH is preferably adjusted to the point best adapted for fermentation.

However, traces of metals or metallic salts may remain in the liquor after the treatment with metal or metal salts and alkaline material, as lime, and the astringents may not have been altogether eliminated. It is preferable, therefore, before proceeding to ferment, to'give the alkaline liquor a treatment with H28. Upon the liquor being so treated, a, dark precipitate is formed. Upon filtering out such precipitate, a light-colored fermentable filtrate is secured which is thoroughly free from bitter or puckery taste and better adapted for fermentation purposes. It is believed that this dark precipitated material includes complex metallic salts of the organic astringents, tanning, and the like which remained in the alkaline solution, together with metal sulfides. Before subjectiori to fermentation the pH is suitably adjusted and the liquor diluted to the concentration desired for the fermentation.

We claim:

1. The process of clarifying wood liquors, obtained through acid hydrolysis of wood, for fermentation, which comprises subjecting the liquor to acid hydrolysis, washing the liquor with a water-immiscible organic solvent containing a compound chosen from the group consisting of butyl alcohol, furfural and isopropylether, heatin: the liquor to remove excess organic solvent, adding metal chosen from the group consisting of iron and aluminum to the acid liquor in sumcient quantity to react with the acid in the liquor, adding lime in sufficient quantity to raise the pH of the solution to between 7 and 8.5 which precipitates astringent materials toxic to fermentation, and removing the precipitatei'rom the clarified liquor.

2. The process as defined in claim 1, and in which the clarified liquor is further treated with hydrogen sulfide and the resulting precipitate removed.

3. The process as defined-in claim 1, and in which the added metal is in a finely divided form. 4. The process as defined in claim 1, and in which the added metal is in the form of a metal salt which will react with the acid in the liquor.

5. Process of clarifying wood liquors, obtained through acid hydrolysis of wood, containing pentosans and hexosans to' provide sugar liquors I freed from materials which are toxic to fermentation, which comprises subjecting the wood liquor to hydrolysis in the presence of a mineral acid to form pentose and hexose sugars, washing the liquor with a water-immiscible organic solvent containing a compound chosen from the group consisting of butyl'alcohol, furi'ural and isopropyl ether, heating the liquor to remove excess organic solvent, adding metal chosen from the group consisting of iron and aluminum to the acid liquor in suilicient quantity to react with the acid in the liquor, adding lime in suillcient quantity to raise the pH of the sugarsolution to between about 7 and 8.5 which precipitates astringent materials toxic to fermentation, and removing the precipitate from the clarified liquor.

6. The process as defined in claim 5, and in which the clarified liquor is further treated with hydrogen sulfide and the resulting precipitate removed.

7. The process as defined in claim 5, and in which the added metal is in a finely divided form.

8. The process as defined in claim 5, and in which the added metal is in the form of a metal salt which will react with the acid in the liquor.

ROBERT M. BOEHM. HORACE E. HALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS OTHER REFERENCES snow-Researches In Oil 8: Proteids Extraction From Soy-Bean, Ch. XV, page 164.

Schroke-Tech. Assn. Papers, Series IX, No. 69, 1919. Abstract D. R. P. 307, 383 and the addition Patent 310, 318 E. Jacoby, page 151.

Carbide 8: Carbon-Synth. Org, Chem, 10th edition. 

